Hyatt.] 78 [Aprils, 
Ilneckel :illii(los in general terms to tlie law of abbreviated 
developnient in his "Morphologie der organisnien," and in his 
"Anthropogenie" pubUslied in 1874 substantially agrees with Cope 
in liis view of the law and uses the term "palingenesis" for tlie 
exact repetition of cliaracteristics which occurs in the earlier and 
simpler forms of a phylum, and ''cenogenesis" for the abbreviated 
or highly accelerated cases of inexact parallelism of the young of 
more complex forms with tlieir ancestors.^ 
1 During the writing of this paper I took from Cope the statement made above 
although unable to find any verification of it in Haeckel's Anthropogenie (1st and 2d 
editions botli dated 1874), but since the above was in press I obtained a copy of the 
4th edition (1891) and the reading of this has caused me to entirely alter my opinion 
with regard to Haeckel's opinions. He certainly had at that time, 1891, what seems 
to me erroneous and inadequate views of the nature and action of the laws of tachy- 
genesis and gave it too limited application. He also used the terms palingenesis and 
cenogenesis differently from the way in which Cope and others have used them in 
this country. 
Haeckel states (Anthropogenie, 4th edition, p. 9, Leipzig, 1891) that "Palingenetische 
processe oder keimesgeschichtliche wiederholungen nennen wir alle jene erschein- 
ungen in der individuellen entwickelungsgeschichte, welche durcli die conservative 
vererbung getreu von generation zu generation iibertragen worden sind und 
welche demnach einen unmittelbaren riickschluss auf entsprechende vorgiinge in 
der stammesgeschichte der entwickelten vorfahren gestatten. Cenogenetische 
processe hingegen oder keimesgeschichtliche storungen nennen wir alle jene 
vorgiinge in der keimesgeschichte, welche nicht auf seiche vererbung von uralten 
stammformen zuriickfiihrbar, vielmehr ernt spdter durch anpassung der keiine oder 
derjuyendform an bestimmte bedingungen der keimesentwickelung hiuzugekommen 
sind. Diese onogenetischen erscheinungen sind frerade zuthaten welche durchaus 
keinen unmittelbaren schluss auf entsprechende vorganfje in der stammesgeschichte 
der ahnenreihe ei-lauben, vielmehr die erkenntniss der letzteren geradeza falschen 
und verdecken." 
So far as one can get at Haeckel's opinions from such expressions as the above, it 
is obvious that he views shortened or abbreviated development in a very distinct 
light from that to which I am accustomed. He speaks of it as due to the introduction 
of "fremde zuthaten," as "cenogenie oder storungsgeschichte" and further, to 
/nake his meaning clearer, on page II he divides cenogenetic phenomena into "Orts- 
verschiebungen oder heterotopien" and on page 12 "Zeitverschiebungen oder hetero- 
chronien." Organs or parts may be developed heterotopically, that is, out of place or 
in a different part of the body from that in which they originated ; or heterochronically, 
that is, earlier in time during the life of the individual than that in which they origi- 
nated, and he also speaks of the latter as "ontogenetische acceler.ation" using exactly 
the adjective applied in this country many j'ears beforehand but that fact does not 
seem to have been considered worthy of his attention, Haeckel then proceeds to add: 
"Das umgekehrte gilt von der verspateten ausbildung des darmcanals, der lei- 
beshohle, der geschlechtsorgane. Hier liegt offenbar eine verzogerung oder verspa- 
tung, eine ontogenetische retardation." This is probably what Cope alludes to in 
his quotation of Haeckel and certainly this is a restatement of Cope's law of retardation 
with, however, the omissiou of any reference to the original discoverer. It will 
